This invention relates to systems for receiving audio and video signals and, more particularly, to systems which may store audio/video information.
A television set may receive an audio/video, or A/V, signal, which combines audio and video data. Increasingly, the A/V signal may be combined with other content, such as closed caption messages, program sub-titles, and even web pages. The A/V signal may enter the television set from a cable wire, a broadcast signal, or from a satellite signal, to name a few.
For example, the television set may receive a variety of programming choices from the connection of a single cable wire. This is so because a cable service provider receives multiple signals, typically from multiple content providers and combines the signals together. The service provider may then broadcast the multiplexed signal over the single cable wire, which may then reach hundreds of thousands of homes.
Both the service provider (cable company) and the content providers (network studios) generate revenue from the content of the multiplexed signal. Accordingly, to prevent piracy, the signal is typically encoded or encrypted during transmission. At the receiving end of the cable wire, a “cable box” or other mechanism may descramble or decrypt the signal for each paying household.
Although television sets are well-known receivers of signals from cable service providers or other sources, other receivers are becoming more widely available. For example, a set-top box is a processor-based system that works with a television set. Set-top boxes are emerging as popular enhancements to television sets because they add features traditionally associated with personal computers to the television experience. For one, set-top boxes may include random access non-volatile storage capability, such as hard disk drives, compact disk read only memories (CD ROMs), or digital video disk random access memories (DVD RAMs).
Broadcast store and replay, or BSR, is the ability of a receiver, such as a set-top box, to locally store portions of an audio/video signal, whether for short periods of time or for extended periods. Similar to using a video cassette recorder, or VCR, a set-top box user may store audio/video content on the random access storage of the set-top box itself.
Audio/video, or A/V, content, stored on the set-top box, may be time-shifted. In other words, much like VCR tapes, the stored content may be played some time after being broadcast. Until the content is retrieved for viewing, it remains stored in the set-top box.
Particularly for receivers which are connected to a network, the stored A/V content of a receiver may be vulnerable to surreptitious behavior, such as piracy. The media storing the A/V content may be connected to other circuitry by a bus. If the bus is open, e.g., accessible to other software or hardware, the A/V content may be copied.
For example, some receivers may include a peripheral component interconnect, or PCI, bus. The PCI bus is compliant with the PCI Local Bus Specification, Revision 2.2 (Jun. 8, 1998, available from the PCI Special Interest Group, Portland, Oreg. 97214). The PCI bus is an open bus with well-known, publicly available specifications.
Alternatively, the media of the receiver may be removable, such as those including a removable hard disk drive. With removable media, the stored A/V content may be sent to another receiver. Thus, for some receivers, the stored A/V content may be stolen.
Further, for receivers which are connected to other receivers, the stored A/V content may be downloaded to another site without leaving evidence of having been downloaded. An entire network of receivers, for example, may potentially retrieve the stored content from a single paying site.
Thus, there is a continuing need to provide protection for revenue-generating or other protection-needing audio/video content when stored on the random access media of a set-top box.